1. Field of the Invention
The present invention relates to a multidirectional input device for an input operation unit of various kinds of electronic apparatuses. More specifically, the present invention relates to a multidirectional input device in which a slider can be operated on a horizontal plane to detect a signal corresponding to an operating direction of the slider.
2. Description of the Related Art
Generally, a multidirectional input device comprises four sets of push switches mounted on a board at equal intervals of 90 degrees and a driving body rockably disposed above the push switches. The driving body is biased to a neutral position by an elastic force of a return spring built in each push switch or by an exclusive return spring. A driving rod protrudes from the center of the driving body. When an operator operates the driving rod in a predetermined direction to be tilted with his or her hand, the driving body is rocked in the desired direction to turn on the desired push switch.
Conventionally, in a haptic controller with a force feedback function, a multidirectional input device is known in which an operating knob and a motor applying an external force to the operating knob are integrally attached to a slider, and an operator slides the operating knob in a desired direction on the horizontal plane, to rock the driving body by the slider. (Refer to Japanese Unexamined Patent Application Publication No. 2001-109558 (Page 9, FIG. 3A)).
FIG. 9 is a cross-sectional view showing a conventional example of such a multidirectional input device. FIG. 10 is a plan view showing the positional relationship between the slider and the driving body which are included in the conventional multidirectional input device. As shown in FIGS. 9 and 10, a rubber 2 is placed on a printed board 1, and a holder 3 stands at the center of the rubber 2. Four bulging portions 2a are integrally formed with the rubber 2, and the bulging portions 2a are formed at equal intervals of 90 degrees on a concentric circle P (FIG. 10) centered on the holder 3. A movable contact 4 is formed at the inner bottom of each of the bulging portions 2a, and a fixed contact 5 is formed on the printed board 1 so as to face the respective movable contact 4 with predetermined spacing. One set of push switch S is composed of a pair of the movable and fixed contacts 4 and 5, and collectively, four sets of push switches S1 to S4 are arranged around the holder 3 at equal intervals of 90 degrees. As shown in FIG. 10, when X-Y rectangular coordinates having the holder 3 as its origin is set, the push switches S1 and S3 are disposed opposite to each other about the origin on the Y-axis and the push switches S2 and S4 are disposed opposite to each other about the origin on the X-axis. A driving body 5 is placed on the bulging portions 2a, and the bottom center of the driving body 5 is pivotally supported by the holder 3. A driving rod 5a stands on the top center of the driving body 5, and a base (lower end) of the driving rod 5a is formed into a semispherical portion 5b. A lower end of a conical portion 6a, extending down from a casing 6, abuts an outer peripheral face of the semispherical portion 5b. The driving rod 5a is inserted through a hole 6b in the conical portion 6a and extends upward. A slider 7 is disposed above the casing 6 and the slider 7 is horizontally movable integrally with an operating knob (not shown). A circular opening 8 is formed in the slider 7, and the driving rod 5a is inserted through the opening 8 and extends beyond the slider 7.
In the multidirectional input device constructed as above, in a non-operating state in which no external force is applied to the operating knob, the driving body 5 maintains neutrality by an upward elastic force from the respective portions 2a, and all the respective push switches S1 to S4 are turned off. As shown in FIG. 10, in the non-operating state, the driving rod 5a of the driving body 5 is disposed at the center of the opening 8 and an equal width of clearance is secured between the driving rod 5a and the opening 8 along the circumference. On the other hand, when an operator moves the slider 7 by the operating knob in any direction, for instance, upward on the Y-axis as shown in FIG. 10, the inner peripheral face of the opening 8 abuts the driving rod 5a to rock (tilt) the driving body 5 in the same direction about the holder 3 as its fulcrum, and to buckle the bulging portion 2a of the rubber 2 disposed in the same direction. As a result, the movable contact 4 of the push switch S1 contacts the facing fixed contact 5. When the slider 714 is moved in a direction inclined at 45 degrees with respect to the X-Y axis, for instance, in a direction inclined at 45 degrees to the upper right in FIG. 10, the driving body 5 rocks in the same direction about the holder 3 as its fulcrum. As a result, the two sets of push switches S1 and S2 corresponding to the direction are simultaneously turned on. Therefore, by selectively operating four sets of push switches S1 to S4 independently or in pairs, the movement of the slider 7 in eight directions can be detected.
However, in the conventional input device described above, it is difficult to accurately manage the relative position between the driving rod 5a of the driving body 5 and the opening 8 of the slider 7. In some cases, the relative position between the driving rod 5a and the opening 8 may be changed due to the assembling errors and the dimensional errors of respective members, and as shown in FIG. 11, the driving rod 5a may be assembled out of the center of the opening 8. In this case, in a non-actuating state of the slider 7, the driving body 5 is slightly pre-tilted. Thus, for instance, when the slider 7 is moved in a direction inclined at 45 degrees to the upper right, one switch (S1 in this case) of the two bulging portions 2a disposed in the desired direction is first turned on. As a result, two sets of push switches S1 to S2 are not simultaneously turned on, which causes an inaccurate detection.